TencentOS Server 4: dovecot (TSSA-2024:1065)

high Nessus Plugin ID 239781

Synopsis

The remote TencentOS Server 4 host is missing one or more security updates.

Description

The version of Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2024:1065 advisory.

Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

CVE-2024-23184:
Having a large number of address headers (From, To, Cc, Bcc, etc.) becomes excessively CPU intensive. With 100k header lines CPU usage is already 12 seconds, and in a production environment we observed 500k header lines taking 18 minutes to parse. Since this can be triggered by external actors sending emails to a victim, this is a security issue. An external attacker can send specially crafted messages that consume target system resources and cause outage. One can implement restrictions on address headers on MTA component preceding Dovecot. No publicly available exploits are known.

CVE-2024-23185:
Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up full_value buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.

Tenable has extracted the preceding description block directly from the Tencent Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

Plugin Details

Severity: High

ID: 239781

File Name: tencentos_TSSA_2024_1065.nasl

Version: 1.1

Type: local

Family: Tencent Local Security Checks

Published: 6/16/2025

Updated: 6/16/2025

Supported Sensors: Nessus

Vulnerability Information

CPE: p-cpe:/a:tencent:tencentos_server:dovecot, cpe:/o:tencent:tencentos_server:4

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/etc/os-release, Host/TencentOS/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 12/5/2024

Vulnerability Publication Date: 12/5/2024

Detections

Analytics